1. Field of the Invention
The present invention relates generally to a vehicle service tool, and more particularly to an improved manual/pneumatic pump structure.
2. Description of the Related Art
A conventional manual/pneumatic pump can be operated manually or pneumatically. The manual/pneumatic pump has a closed space for collecting fuel. When the air pressure in the closed space is lowered, due to the atmosphere, the fuel is sucked into the closed space to facilitate maintenance/repair of a vehicle.
FIGS. 1 and 2 show a valve assembly 90 with a float member, which is disclosed in prior art. The valve assembly 90 including a check valve 91 and a float member 92 are integrated into a one-piece member. The one-piece member is installed in an intake 94 of a vacuum generator 93, which sucks air on the basis of Venturi tube principle. Accordingly, the check valve 91 is forced by a spring 911 to make a ball member 912 normally block a bottom opening of the intake 94. Under such circumstance, the intake 94 is not in communication with the internal space 95 of the fuel collection reservoir of the manual/pneumatic pump. In this case, a user can manually operate the manual/pneumatic pump to pump the external fuel into the fuel collection space.
When the manual/pneumatic pump is operated pneumatically, the external compressed air is filled into the vacuum generator 93. Under Venturi tube effect, the air pressure in the intake 94 is lowered. At this time, the pressure in the fuel collection space 95 under the ball member 912 is higher so that the ball member 912 is pushed away. Under such circumstance, the intake 94 is in communication with the fuel collection space 95 to suck the gas out of the fuel collection space 95 and create a low-pressure environment. When the fuel in the fuel collection space 95 reaches the full level, the float member 92 moves upward due to the buoyancy, whereby the sealing washer 921 at the top of the float member 92 blocks the bottom opening of the intake 94. Accordingly, the gas in the fuel collection space 95 is prevented from being further sucked out so as not to over-pump the fuel.
When the float member 92 moves upward and the washer 921 blocks the bottom opening of the intake 94, the space S between the washer 921 and the ball member 912 is closed and kept in a near-vacuum low-pressure state. In this case, the higher pressure of the lower side of the washer 921 may hinder the washer from unblocking the bottom opening of the intake 94. As a result, it is hard for the float member 92 to drop under gravity.